sun and stars - stanford solar centersolar-center.stanford.edu/activities/sunandstars5-8.pdf · 5....

Sun and Stars

Supplemental science materials

for grades 5 - 8

Curriculum Specialist

Solar Astronomers

Page Layout and Design

These supplemental curriculum materials are sponsored by theStanford SOLAR (Solar On-Line Activity Resources) Center. Inconjunction with NASA and the Learning Technologies Channel.

Susanne AshbySusanne AshbySusanne AshbySusanne AshbySusanne Ashby

Paul MortfieldPaul MortfieldPaul MortfieldPaul MortfieldPaul MortfieldTodd HoeksemaTodd HoeksemaTodd HoeksemaTodd HoeksemaTodd Hoeksema

Amberlee ChausseeAmberlee ChausseeAmberlee ChausseeAmberlee ChausseeAmberlee Chaussee

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Table of Contents

Teacher OverviewObjectivesScience ConceptsCorrelation to the National Science StandardsSegment Content/On-line Component ReviewMaterials List

ExplorationsScience Explorations• Sizing Up the Stars• From a Distance• Wavelength and Energy• Resonance Rings• Spectroscopic Observations

Career Explorations (see the Web site for more about these careers)• Laser Light Show technician• Solar Scientist• Astrophysicist• Forensic Scientist

Answer Keys• Student Worksheet: Our Sun is a Special Star• Student Worksheet: The Electromagnetic Spectrum• Science Exploration Guidesheet: Spectroscopic Observation #3

Student Handouts• Student Reading: Our Sun is a Special Star• Student Worksheet: Our Sun is a Special Star• Student Reading: The Electromagnetic Spectrum• Student Worksheet: The Electromagnetic Spectrum• Student Reading: Spectroscopy: Star Light, Star Bright• Science Exploration Guidesheet: Sizing Up the Stars• Science Exploration Guidesheet: From a Distance• Science Exploration Guidesheet: Spectroscopic Observation #1: Observing Spectra• Science Exploration Guidesheet: Spectroscopic Observation #2: Mystery Gas Tube• Science Exploration Guidesheet: Spectroscopic Observation #3: Solar Spectrum• Career Exploration Guidesheet: Compare Two Careers

Appendix• Solar Glossary• Web Work

• Objectives

• Science Concepts

• Correlation to the National Science Standards

• Segment Content/On-line Component Review

• Materials List

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Teacher Overview

Objectives

1. Students will observe that the visible spectrum is only a part of what our sun, a star, emitswithin the electromagnetic spectrum.

2. Students will study how astronomers use special tools (spectroscope) to learn more aboutobjects that are so far away.

3. Students will observe how white light can be refracted to form a color spectrum that has apattern.

4. Students will learn what spectroscopic data can specifically tell astronomers about the sun andother stars.

5. Students will observe a Doppler Shift and what it indicates about a celestial object.

6. Students will determine that the distance of an object from an observer affects the appar-ent size of said object.

7. Students will see how other careers are connected to spectroscopy.

8. Students will understand how technological design can help scientists to better understand ourEarth, our Sun, our solar system and the universe around us.

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Teacher Overview

Science Concepts

1. Our sun is really a star in that it has the same characteristics as the other stars visible in thesky, but because it is the closest star to Earth and the Earth revolves around it, it is also calledthe Sun.

2. The sun contains different kinds of hot gases that interact in a special way to give off heat,light and other kinds of energy which can be classified as the electromagnetic spectrum.

3. Scientists use technological design to develop tools such as a spectroscope to learn moreabout celestial objects. Spectroscopic analysis tells what elements the celestial object is burn-ing, if it is moving away or towards Earth, tells us its temperature which way an object isrotating and how fast. (Doppler Shift, Emission Lines)

4. The Sun gives off light we can see. It is white light that we can bend or refract. When refract-ing white light we get colors like in a “rainbow” (ROY G BIV) which is known as the colorspectrum.

5. The electromagnetic spectrum is composed of various forms of light arranged according totheir increasing frequency and decreasing wavelength. See diagram below.

The Electromagnetic SpectrumThe Electromagnetic SpectrumThe Electromagnetic SpectrumThe Electromagnetic SpectrumThe Electromagnetic Spectrum

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Teacher Overview

Correlation to the National Science Standards

Grades 5 - 8

This segment of the Webcast All About the Sun, “Sun and Stars”, is brought to you by acorrelation to the National Science Standards for grades 5 - 8 as delineated below.

Unifying Concepts and Processes• Evidence, models, and explanation• Changes, constancy, and measurement• Form and function

Science as Inquiry• Abilities necessary to do scientific inquiry

• Identify questions that can be answered through scientific investigation• Design and conduct a scientific investigation• Use appropriate tools and techniques to gather, analyze and interpret data.• Develop descriptions, explanations, and predictions, and models using evidence• Think critically and logically to make the relationships between evidence and

explanations• Understandings about scientific inquiry

Physical Science• Transfer of energy

Earth and Space Science• Structure of the Earth system• Earth in the solar system

Science and Technology• Abilities of technological design• Identify appropriate problems for technological design• Design a solution or product• Implement a proposed design• Evaluate completed technological products or designs• Communicate the process of technological design• Understandings about science and technology

Science in Personal and Social Perspectives• Science and technology in society

History and Nature of Science• Science as a human endeavor• Nature of science

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Teacher Overview

Segment Content/On-line Component Review

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Teacher Overview

Materials List

Science Exploration

••••• Sizing Up the StarsSizing Up the StarsSizing Up the StarsSizing Up the StarsSizing Up the Stars

Per small group, partner, or small team• Long, flat surface (table, counter top, sidewalk)• Two identically sized round objects (tennis ball, rubber racquetball, golf ball, ping

pong ball, balled up sheets of paper, marble, bubblegum ball, etc. (These roundobjects are listed according to size.)

• 1 round object of a slightly smaller size than the other two round objects (For example,if a group has two tennis balls, then the smaller round object should be a rubberracquetball or golf ball.)

• Measuring tape or meter stick (The students will need to be able to mark and measuredistances.)

• ruler• Student Guidesheet: Sizing Up the Stars

••••• From a DistanceFrom a DistanceFrom a DistanceFrom a DistanceFrom a Distance

• Using the materials listed below construct the following• “Mystery Light Source” (see diagram “A”):• yellow balloon• petroleum jelly (enough to fill the balloon to a diameter of at least 2 inches)• flashlight• small box (the same height as the flashlight when standing with light end facing up)• Diagram “A”:

small boxsmall boxsmall boxsmall boxsmall box

flashlightflashlightflashlightflashlightflashlight

hole at top of boxhole at top of boxhole at top of boxhole at top of boxhole at top of box

Petroleum jelly filled balloonPetroleum jelly filled balloonPetroleum jelly filled balloonPetroleum jelly filled balloonPetroleum jelly filled balloon

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Teacher Overview

Materials List (continued)

••••• From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)

• *Mystery Light Source” Box (see diagram “B”):• 3’ by 3’ box (It needs to be large enough and dark enough to sufficiently hide what the

light source inside is.)• 1” wide and 3” to 4” long viewing station (one per side)• Diagram “B”:

••••• Wavelength and EnergyWavelength and EnergyWavelength and EnergyWavelength and EnergyWavelength and Energy• Rope approximately 30 – 50 feet in length• Long, smooth-surface floor

••••• Resonance RingsResonance RingsResonance RingsResonance RingsResonance Rings• Used lightweight file folders or similar weight construction paper from which to cut

strips 3 cm x 30 cm and 3 cm x 35 cm (one of each per student pair or work group)• Cardboard sheets about 20 cm x 30 cm (one per student pair or work group)• Masking tape• Scissors• cm measuring tool

3 ft.

3 ft.

3 ft.

3 ft.

3 ft.

3 ft.3 ft.3 ft.3 ft.3 ft.

3 ft.3 ft.3 ft.3 ft.3 ft.

1”1”1”1”1”3” - 4”3” - 4”3” - 4”3” - 4”3” - 4”

1”1”1”1”1”3”

- 4”

3” -

4”

3” -

4”

3” -

4”

3” -

4”

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Teacher Overview

Materials List (continued)

••••• Spectroscopic ObservationsSpectroscopic ObservationsSpectroscopic ObservationsSpectroscopic ObservationsSpectroscopic Observations• Spectroscope

• Spectroscope poster (with scope template and directions)• To order this invaluable poster check the Web site:

http://solar-center.stanford.edu/poster• 11” x 17” spectroscope template sheet• 11” x 17” black card stock• Diffraction Grating

• Edmund Scientific 609-573-6250• Catalog # F39502 $23.60 for a package of 25• Catalog #F50183 $58.00 for package of 80

• Scissors• Straight edge (used to bend the cardboard)• Clear tape• Glue stick

• Gas tubes or Web site’s spectra for spectral analysis

• Student Guidesheet: Spectroscopic Observations #1, #2 & #3

• Science Explorations

• Sizing Up the Stars

• From a Distance

• Wavelength and Energy

• Resonance Rings

• Spectroscopic Observations

• #1: Observing Spectra

• #2: Mystery Gas Tube

• #3: Solar Spectrum

• Career Explorations

(see the Web site for more about these careers)

• Solar Scientist

• Astrophysicist

• Aquaculturist

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Science Exploration Guidesheet

Science Explorations

••••• Sizing Up the StarsSizing Up the StarsSizing Up the StarsSizing Up the StarsSizing Up the Stars

Purpose: This activity is designed to get students to observe that two objects of equal sizecan appear to be of different sizes when placed at a greater or lesser distance from theobserver. This is intended to assist students in visualizing that the sun is actually quite asmall star compared to other stars, but because our planet is so much closer to the sunthan to any other star, the sun appears much larger.

Distribute the student guidesheet Sizing Up the Distance and review the directions for theactivity. Instruct the students to place and hold the round object on the table while measur-ing from the front edge of the round object emphasizing the importance of consistency inmeasurement for accuracy. Remind the students that when they are observing they shouldplace their “eyes” in the same place each time, perhaps placing their chin directly on theflat surface.

The questions on the guidesheet will lead the students to develop a procedure similar towhat is given below:• Place the two equal size round objects 30 cm apart and 90 cm from the observer’s

eyes (the edge of the flat surface).

• Observe and compare the apparent size of the round objects.

• Leave the round object on the right in its position. Maintaining the 30 cm separationbetween the two equal size round objects, place the left one at a closer distance to theobserver from the one on the right.


• Leave the round object on the right in its position. Maintaining the 30 cm separationbetween the two equal size round objects, place the left one at a greater distance tothe observer than the right round object is.


• Repeat the procedure except leave the left round object in place while moving the rightround object closer and farther away from the observer.

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Science Explorations (continued)

••••• Sizing Up the Stars (continued)Sizing Up the Stars (continued)Sizing Up the Stars (continued)Sizing Up the Stars (continued)Sizing Up the Stars (continued)

• Using one small round object and one larger round object, the students will be askedto place the round objects in such a way as to make them appear the same size. Note:Based upon their previous observations, the students should be able to ascertain that tomake the smaller round object appear equal in size to the larger object, it must beplaced closer to the observer than the larger round object.

• Using one small round object and one larger round object, the students will be askedto place the round objects in such a way as to make the smaller round object appearlarger than the larger sized round object. Note: Based upon their previous observa-tions, the students should be able to ascertain that to make the small round objectappear larger it must be placed even closer to the observer than where it was placedpreviously OR the larger round object will need to be moved farther back than where ithad been previously placed.

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••••• From a Distance From a Distance From a Distance From a Distance From a Distance

Purpose: Students will utilize their abilities for technological design to perform scienceinquiry by proposing methods for obtaining information about a faraway object withoutbeing able to handle it or get close to it. The students will see how sometimes the inquirythat drives science is what drives the development of technology.

• To develop the “Mystery Light Box” for this activity, follow the instructions found underthis activity’s name in the Materials section.

• Have students work in small groups of two to four, following the instructions on theirstudent guidesheet, and answering the questions.

• Review with the students the directions for the activity as stated on the ScienceExploration Guidesheet: Mystery Box Light

• The students are to observe what is in the box and draw what they see.

• Have students brainstorm in small groups what kind of questions they would likeanswered about the light source in the Mystery Light Box. Post the lists and decide upon3 -5 questions that they will answer.

• Back in their small groups, they discuss ways (2 to 4) they can answer these questionsabout this mystery light without doing the following:• removing the object from the box• removing the box from above the object• shining a light into the box• reaching in with their hands to touch it

• After a brief explanation of how the search for answers leads scientists to invent betterways to find answers (through technological design), have your students return to theirsmall groups and brainstorm 2 to 4 design suggestions that will help to answer eachquestion. Assure them not to worry about whether it is possible to create the techno-logical tools in class or not, but to simply come up with the new ideas for technologicaldesign.

• Have the small groups post their ideas for ways to obtain answers to the questions.

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••••• From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)• In a whole class forum, the students share their suggestions and the class then votes on

the most feasible methods that the students themselves could actually perform.

• Ask students to determine what materials will be needed and have these materialsavailable for the next session when these new designs will be used to find the answersto the questions.

• For the next class session have the necessary materials and assign each small groupone or two questions to answer.

• Then use the remainder of the class session for the small groups to development, test,refine and use the design to gather the information.

• Depending upon the amount of time it will take for the students to perform their tests(as there will probably be only one Mystery Light Box), this might require another classsession. Students could also be given alternative tasks to do while awaiting their oppor-tunity to gather the information from the Mystery Light Box.

• Example Note: Below is a breakdown of the types of questions the students might wishto have answered followed by the type of technological design ideas they might sug-gest. This is provided to give an idea of just how this activity could evolve.

• Types of Questions about the mystery light source:• What is it made of inside?• What is its temperature?• How does it make its light?• What is its energy source?• How large (or small) is it?

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Science Explorations

••••• From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)From a Distance (continued)• Technological designs to assist in gathering the information needed to answer the

questions:• Create a probe that acts like a syringe and can be remotely stuck into the mystery

light source using a long stick. The material inside could then be brought out forfurther examination.

• Place a thermometer on a long stick and remotely “take the temperature” of thelight source.

• Use the spectroscope to analyze what type of light it is generating.• Take close-up (flash) photo pictures to reveal more about the light source• Look at it with binoculars• Develop a way to measure its size from a distance (such as measuring how far

away it is from the viewing point and the angle created from its width).

••••• Wavelength and EnergyWavelength and EnergyWavelength and EnergyWavelength and EnergyWavelength and Energy• This activity provides a graphic demonstration of the relationship between energy and

wavelength and should be included as part of a discussion about the electromagneticspectrum. High-frequency waves (short wavelength) represent more energy than low-frequency (long wavelength) waves. This activity is easiest to observe when done on asmooth floor surface.

• Select 2 students to hold opposite ends of a 30 - 50 foot rope.• While 1 end of the rope is held still, have the other student shake the opposite end up

and down at a moderate, but steady rate.

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••••• Wavelength and Energy (continued)Wavelength and Energy (continued)Wavelength and Energy (continued)Wavelength and Energy (continued)Wavelength and Energy (continued)• Ask the remaining students to observe the wave patterns created in the rope. Point out

wave crests. Ask students to estimate the wavelength and frequency of waves reachingthe other student. The wavelength is the distance from wave crest to wave crest. Fre-quency is the number of waves reaching the far end of the rope each second.

• Have the student shaking the rope shake it a little faster. Again have the studentsestimate the wavelength and frequency.

• Have the student shaking the rope shake the rope as quickly as he or she can. Again,have the class estimate the wavelength and frequency.

• Stop the demonstration and ask the student shaking the rope if it is easier to producelow frequency waves (short wavelength) or high frequency (short wavelength) waves.

• Discuss the implications this demonstration has for the electromagnetic spectrum.

••••• Resonance RingsResonance RingsResonance RingsResonance RingsResonance Rings• All objects have a natural frequency at which they vibrate. When the frequency of the

shaking matches the frequency of one of the rings in this activity, it begins to vibratemore than the rest. In other words, some of the energy in the shaking is absorbed bythat ring. This effect is called resonance.

• Resonance takes place when energy of the right frequency (or multiples of the rightfrequency) is added to an object causing it to vibrate.

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••••• Resonance RingsResonance RingsResonance RingsResonance RingsResonance Rings (continued)(continued)(continued)(continued)(continued)• When electromagnetic radiation enters the Earth’s atmosphere, certain wavelengths

match the natural frequencies of atoms and molecules of various atmospheric gasessuch as nitrogen and ozone. When this happens, the energy in those wavelengths isabsorbed by those atoms or molecules, intercepting this energy before it can reach theEarth’s surface.

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••••• Resonance RingsResonance RingsResonance RingsResonance RingsResonance Rings (continued)(continued)(continued)(continued)(continued)• Wavelengths that do not match the frequencies of the atoms and molecules found in

the gases present will pass on through to the Earth’s surface.

• Resonance is important to astronomy for another reason. All starlight begins in thecenter of the star as a product of nuclear fusion. As the radiation emerges from thephotosphere or surface of the star, some wavelengths of radiation may be missing. Themissing components produce dark lines in the star’s spectra, called absorption lines.These lines are created as the radiation passes through the outer gaseous layers of thestar. Some of that radiation will be absorbed as various gas atoms which are presentbegin to resonate. Absorption lines (dark lines in a star’s spectra) tell scientists whatelements are present in the outer gaseous layers of the star.

• Procedures for this exploration:• Cut 2 strips of paper from used file folders. One strip should be 3 cm wide and

approximately 30 cm in length, with the other being 3 cm wide and 35 cm inlength.

• Curl each strip into a cylinder and tape the ends together.• Tape the cylinders to the cardboard as shown in the diagram below. (Note: If the

ring has a crease in it, the crease should be at the bottom.)

• Holding the cardboard, slowly shake it back and forth.• Gradually increase the frequency of the shaking.• Observe what happens when the frequency of the shaking is gradually increased.

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••••• Spectroscopic ObservationsSpectroscopic ObservationsSpectroscopic ObservationsSpectroscopic ObservationsSpectroscopic Observations

For these activities students will construct their own spectroscope, observe common lightsources, record their spectra and compare their findings with fellow classroom scientists.

For directions to build a spectroscope, see the Spectroscope Poster (purchase informationfound in the Materials List. Allow approximately 3 class sessions to construct and calibratethe spectroscopes before having students perform these science explorations.

Unlike a prism, which disperses white light into the rainbow colors through refraction, thediffraction grating used in this homemade spectroscope disperses white light through aprocess called interference The grating used for this spectroscope consists of a transpar-ent piece of plastic with many thousands of microscopic parallel grooves. Light passingbetween these grooves is dispersed into its component wavelengths and appears as paral-lel bands of color on the retina of the observer’s eyes.

••••• Spectroscopic Observation #1: Observing SpectraSpectroscopic Observation #1: Observing SpectraSpectroscopic Observation #1: Observing SpectraSpectroscopic Observation #1: Observing SpectraSpectroscopic Observation #1: Observing SpectraStudents observe common light sources, record their spectra and compare their findingswith fellow classroom scientists.

••••• Spectroscopic Observation #2: Mystery Gas TubesSpectroscopic Observation #2: Mystery Gas TubesSpectroscopic Observation #2: Mystery Gas TubesSpectroscopic Observation #2: Mystery Gas TubesSpectroscopic Observation #2: Mystery Gas TubesTeacher purchases in advance 3 - 5 gas tubes (recommended helium, hydrogen, mercury,neon and water). Do not tell the students what gas is found in each gas tube. Have stu-dents observe each tube using their spectroscopes and record their findings. Then, havethe students compare each spectrum with the Spectra Reference Chart (located on theWeb site or available to be printed on a color printer from this PDF file). Students can nextdetermine which gas is contained in each tube by comparing the spectra they observe andrecord to the reference chart.

••••• Spectroscopic Observation #3: Solar SpectrumSpectroscopic Observation #3: Solar SpectrumSpectroscopic Observation #3: Solar SpectrumSpectroscopic Observation #3: Solar SpectrumSpectroscopic Observation #3: Solar SpectrumHave students observe sunlight through their spectroscopes by using a white wall to reflectthe sun’s light. Do NOT have students view the sun directly through their spectroscopes.Do NOT have students view the sun directly through their spectroscopes.Do NOT have students view the sun directly through their spectroscopes.Do NOT have students view the sun directly through their spectroscopes.Do NOT have students view the sun directly through their spectroscopes.Students record the solar spectrum. Next, have students compare their solar spectrum withan actual solar spectrum from the Spectra Reference Chart. These will be different simplybecause of the difference in quality between the homemade device and the more precisescientific instrument. Then, review with the students the directions on how to identify ele-ments in the solar spectrum from the Student Guideheet: Solar Spectrum. Finally, have thestudents follow the same procedure and attempt to determine the other elements found inthe sun.

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Career Exploration Guidesheet

Career Explorations

After viewing the Web cast or after reading a brief introduction on the Web site

http://solar-center.stanford.edu

of each of the careers represented, the students should be able to make a comparisonbetween two of the careers highlighted on the Web site.

Students choose two of the careers and place each in the box at the top of the chart. In thebox in the middle, students relate 3 ways in which these careers are similar. In the twoboxes at the lower half of the page, the students will relate 3 ways in which each career isdifferent from the other and select the appropriate criteria. For example, choosing solarscientist and forensic scientist a criterion for a difference would be the object each studies.

• Student Worksheet: Our Sun is a Special Star

• Student Worksheet: The Electromagnetic Spectrum

• Science Exploration Guidesheet: Spectroscopic Observation #3

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Student Worksheet

Our Sun is a Special Star - Key

DirectionsDirectionsDirectionsDirectionsDirections: After reviewing the reading “Our Sun is a Special Star”, answer the questions below.

1. What is a star?

A star is a sphere of hot, glowing gases.

2. What is the sun?

A star which is a sphere of hot, glowing gases.

3. Draw a picture that shows a star, the sun and the earth if they were placed next to each otherin order of largest to smallest.

STAR SUN EARTH

4. Explain why the sun does not look like other stars.

Because the sun is closer to the Earth than any other star it looks much larger and appearsmuch brighter than the other stars in the sky.

5. What kind of energy does the sun give off?

The sun gives off energy we can see (visible light) and energy we cannot see (gamma rays, x-rays, infrared rays).

6. What does a star’s spectrum tell scientists about itself?

A star’s spectrum tells scientist what elements are being used for fuel inside the star. Thisinformation can tell a scientist about the star’s age, its temperature and its life cycle.

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Student Worksheet

The Electromagnetic Spectrum - Key

DirectionsDirectionsDirectionsDirectionsDirections: After absorbing the enlightened words from the reading about the electromagneticspectrum, answer the questions below.

1. List the different types of light form the electromagnetic spectrum that cannot be seen by the eye.

Radio, microwaves, infrared, ultraviolet, x-ray, gamma rays

2. In the first box, draw a radio wave. In the second box, draw an x-ray wave. Tell how a radiowave is different from an x-ray.

Tell how they are different:

Radio waves have low-energy photons that give off a longer wavelength with a lower fre-quency. X-rays have high-energy photons that give off a shorter wavelength with a higherfrequency.

3. Explain in your own words how light is generated. Create a drawing to show yourexplanation.

Electrons whirling about an atom absorb incoming energy. This causes them to reach a level ofexcitation. The electrons spontaneously release the same amount of energy absorbed in the form ofphotons. The amount of energy of the photons released will determine the type of light.

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Spectroscopic Observation #3:Solar Spectrum - Key for page 2 only

Follow this same procedure to compare the other elements found on the Spectra Reference Chartto the Solar Spectrum and list below the elements that the sun is burning. Then, draw the emissionspectrum for each element given.

1. hydrogen

2. helium

3. sodium

4. ___________________

Grades 5 - 8

• Student Reading: Our Sun is a Special Star

• Student Worksheet: Our Sun is a Special Star

• Student Reading: The Electromagnetic Spectrum

• Student Worksheet: The Electromagnetic Spectrum

• Student Reading: Spectroscopy: Star Light, Star Bright

• Science Exploration Guidesheet: Sizing Up the Stars

• Science Exploration Guidesheet: From a Distance• Science Exploration Guidesheet:

Spectroscopic Observation #1: Observing Spectra• Science Exploration Guidesheet:

Spectroscopic Observation #2: Mystery Gas Tube• Science Exploration Guidesheet:

Spectroscopic Observation #3: Solar Spectrum• Career Exploration Guidesheet: Compare Two Careers

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Student Reading

Our Sun is a Special Star

Look up at the night sky and what would you see? You would see manysmall points of light that we call stars. A star is actually a huge spheremany times larger than Earth. A star is a big ball of hot, glowinggases.

Look up at the sky during the day and what would you see? Of themany things in the sky, you would notice the sun. The sun is the biggestand brightest object in the sky during the day. The sun is a huge spheremany times the size of the Earth. The sun is a big ball of hot, glowing gases.

The sun is a star. The sun is not the biggest or brightest star. It is really quite small and ordinarycompared to the many other stars. It only looks like the biggest and brightest star because it is theclosest star to Earth. The sun is about 93 million miles away from the Earth. The second closeststar is 300,000 times farther away from earth than the sun.

The sun gives off lots of energy. It gives off energy we can see and energy we cannot see. Theenergy we can see is called white light. Scientists use this white light to learn more about the sun.The white light can be bent or refracted. When white light is refracted it gives us the colors of arainbow. We call this rainbow a spectrum.

The bands of color in a spectrum always follow the same order: red, orange, yellow, green, blue,indigo and violet. This order occurs because of each color’s frequency. Within the visible spec-trum, red has the lowest frequency and violet has the highest. Some of the color bands might notbe as wide as others. Sometimes a color might not even appear. This is caused by the chemicalelement that is being burned. Each star’s spectrum is different depending upon what elements arefound inside the star.

A star’s spectrum is a lot like a person’s fingerprint. Each star’s spectrum gives a unique colorpattern that only that star has. Much like people and their fingerprints because no two peoplehave the exact same fingerprint pattern. By carefully studying a star’s spectrum, scientists can tellwhat gases and elements the star is burning. The sun’s spectrum shows scientists that it is burningmainly hydrogen and helium.

Even though the sun is the largest object in the sky, it is really a small, ordinary star. It is special tous because it is the closest star to Earth, and gives us light.

SSSSSTUDENTSTUDENTSTUDENTSTUDENTSTUDENTS: NEVER LOOK DIRECTLY AT THE SUN!

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Student Worksheet

Our Sun is a Special Star

DirectionsDirectionsDirectionsDirectionsDirections: After reviewing the reading “Our Sun is a Special Star”, answer the questions below.

1. What is a star?

2. What is the sun?

3. Draw a picture that shows a star, the sun and the earth if they were placed next to each otherin order of largest to smallest.

4. Explain why the sun does not appear the same as other stars.

5. What kind of energy does the sun give off?

6. What does a star’s spectrum tell scientists about itself?

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Student Reading

The Electromagnetic Spectrum

The Excitement of Light

There is more to light than what is visible. We think of light as the visible spectrum which is whitelight and its colors caused by its refraction (red, orange, yellow, green, blue, indigo and violet).There is also, light that is invisible: radio waves, microwaves, x-rays, infrared rays, ultravioletrays and gamma rays. Both forms of light begin in atoms with those tiny electrons moving abouteach nucleus. Electrons carry a specific amount of energy. Electrons can also, absorb moreenergy and release it later. As a neutral atom absorbs more energy in its electrons, it becomesexcited. Later, this excited atom’s electrons will release the absorbed energy in the form of a verytiny packet called a photon. This photon carries only exactly the extra energy that the electronhad absorbed—no less, no more.

Light is made up on these photons. Think of light as being a stream of these photons. Somephotons have more energy than other photons. It depends on how much energy its

electron absorbed and then, released. The amount of energy in a photon willdetermine what kind of light wave is being given off. For example, high-

energy photons will produce x-rays. Moderate-energy photons willgive off visible light. Low-energy photons will give off radio

waves.

Riding the Waves

Light waves are electromagnetic waves. Light waves do not need a medium, or substance, throughwhich to travel. This means they can travel through the vacuum of space, unlike sound waveswhich need a medium like air or water in order to move. As the stream of photons move,they generate electric and magnetic fields. All light waves are trans-verse waves. That means that the direction of these moving photonsis at right angles to the electric and magnetic fields. Just like a soundwave, light waves can be measured by amplitude, wavelength andfrequency. The slower the frequency (or lower the hertz number) theless energetic the wave. For example, the visible spectrum has red at oneend and violet at the other end of the spectrum. Red light has the lowest fre-quency of all the colors. As you move from red light through the spectrum to violet light, thefrequency of the light wave increases. Violet has the greatest frequency and the greatest energy.In measurable terms of hertz (Hz) the visible spectrum contains light waves with frequenciesbetween 400 trillion and 750 trillion hertz.

○○○○○○○○○○○○

○○○○○○

○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

31

Student Reading

The Electromagnetic Spectrum (continued)

Covering the Full Spectrum

Scientists organize the different forms of light by frequency and wavelength. They arrange thesedifferent types of light from lowest to highest frequency. Take a look at the Electromagnetic Spec-trum below. Notice that radio waves are located on the left. The photons of these waves do nothave a lot of energy. They are low frequency waves with a long wavelength. AM radio waveshave a lower frequency than FM waves. Higher frequencies are needed for television signals. Upthe frequency some more and we would have microwaves. Ultraviolet radiation is rated just belowthe visible spectrum’s frequencies. These harmful waves cannot be seen. Most of the ultravioletradiation which comes from the Sun is absorbed in the Earth’s upper atmosphere. On the otherside of the visible spectrum are the high frequency waves with greater energy levels. Here we findthe dangerous, unseen rays of x-rays and gamma rays.

Scientists use the full electromagnetic spectrum to learn more about the sun and the stars. Forexample, radio waves tell scientists about the gases in our galaxy and give details about magneticfields in space. Ultraviolet light studies have mapped the hot gases found throughout the universe.Most of what astronomers have learned about the sun and stars has been contained in the elec-tromagnetic radiation that has traveled to Earth.

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Student Worksheet

The Electromagnetic Spectrum

DirectionsDirectionsDirectionsDirectionsDirections: After absorbing the enlightened words from the reading about the electromagneticspectrum, answer the questions below.

1. List the different types of light form the electromagnetic spectrum that cannot be seen by the eye.

2. In the first box, draw a radio wave. In the second box, draw an x-ray wave. Tell how a radiowave is different from an x-ray.

Radio waveRadio waveRadio waveRadio waveRadio wave

X-rayX-rayX-rayX-rayX-ray

Tell how they are different:Tell how they are different:Tell how they are different:Tell how they are different:Tell how they are different:

3. Explain in your own words how light is generated. Create a drawing to show yourexplanation.

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Student Reading

Spectroscopy: Starlight, Star Bright

Spectroscopes are important tools for astronomy. They enable astronomers to analyzestarlight (and sunlight) by providing a measure of the relative amounts of red and bluelight a star gives off. Knowing this, astronomers can determine a star’s temperature.They can also deduce its chemical composition simply by observing and analyzing itslight.

Starlight is made up of photons. These photons originate from the inside of a star.There, pressures are enormous and nuclear fusion is triggered. Intense radiation isproduced as atoms, consisting of a nucleus surrounded by one or more electrons,collide with each other millions of times each second. The number of collisions de-pends on the temperature of the gas inside the star. The higher the temperature, thegreater the rate of collisions.

Because of these collisions, many electrons are boosted to higher energy levels, aprocess called excitation. The electrons spontaneously drop back to their originalenergy level. In doing so, they release energy as photons. This is what happens to thefilament of an electric light bulb or to an iron bar when it is heated in a furnace. Asthe temperature of the filament rises, it begins to radiate reddish light. When thefilament becomes even hotter, it radiates a bluish light. Thus, the color it radiates is anindicator of the filament’s temperature. Stars that radiate a great amount of red lightare much cooler than stars that radiate a great amount of blue light. Stellar spectratherefore can be used as a star thermometer.

One of the important applications of spectroscopes is their use for identifying chemicalelements. Each chemical element radiates light in specific wavelength combinationsthat are as distinctive as fingerprints. Knowing the “spectral fingerprint” of eachelement enables astronomers to identify the elements present in distant stars by ana-lyzing their spectra.

There are 3 kinds of spectra: continuous, absorption and emission.

When observed through a spectroscope, the continuous spectrum appears as a continuous bandof color ranging from red to violet.

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Student Reading

Spectroscopy: Starlight, Star Bright (continued)

An absorption spectrum happens when the light from a star passes through a cloud of gas beforereaching the spectroscope. For example, let’s say that light from a star passes through a cloud ofhydrogen gas before reaching the spectroscope. Some of the wavelengths of light will be ab-sorbed by the hydrogen atoms. This absorption will produce a spectrum that has a broad band ofcolor interrupted by dark lines. These dark lines represent the certain wavelengths of light thatwere absorbed by the hydrogen cloud.

An emission spectrum is observed when energy is absorbed by the gas atoms in a nebula and isreradiated by those atoms at specific wavelengths. This spectrum consists of bright lines against ablack background. The light from fluorescent tubes and neon lights produce emission spectra.

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Student Reading

Spectroscopy: Starlight, Star Bright (continued)

Stellar spectra allow astronomers to determine a star’s temperature and its chemical composition.This enables astronomers to classify stars into spectral categories, estimate their age andpostulate their life cycle. When available, astronomers prefer stellar spectra collected by orbitingspacecraft over spectra collected by Earth-based telescopes. The Earth’s atmosphere acts as afilter and can give inaccurate readings. Orbiting spacecraft are not affected by the Earth’satmosphere because they orbit above the atmosphere. These orbiting spectroscopes can alsocollect infrared, ultraviolet, x-ray and gamma ray bands that simply do not reach spectroscopeson the ground.

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Sizing Up the Stars

DirectionsDirectionsDirectionsDirectionsDirections: Follow each step below and answer the questions.

1. Take both round objects your teacher gives you and place them on a flat surface 30 cm apartand 1 meter from the observation point. See diagram below. Please, note that the observermust be able to place his/her eyes at eye level with the round objects for this activity.

2. Placing your eyes at eye level to the two round objects, observe the apparent size of eachobject to the other. Do they appear to be the same size?

3. Leaving the round object on the left in the same position, move the round object on the right sothat it appears smaller than the round object on the left. Measure the placement of both roundobjects and record it below on the diagram.

4. Leaving the round object on the left in the same position, move the round object on the right sothat it appears larger than the round object on the left. Measure the placement of both roundobjects and record it below on the diagram.

5. Using what you have learned from steps 3 and 4, replace one of the round objects with asmaller round object. In order for the smaller round object to appear the same size as thelarger round object, predict what the placement of both round objects would be by drawing apicture of it below.

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Sizing Up the Stars (continued)

6. Place both round objects in such a way that the smaller round object appears the same size asthe larger round object. Measure the placement of both round objects and record it below onthe diagram. Was your prediction correct?

7. Use what you have learned from steps 3 and 4 and the same two different sized roundobjects for this next step. In order for the smaller round object to appear larger than thelarger round object, predict what the placement of both round objects would be by drawing apicture of it below.

8. Place both round objects in such a way that the smaller round object appears larger than thelarger round object. Measure the placement of both round objects and record it below on thediagram. Was your prediction correct?

9. Explain how it is possible that the sun in our solar system can actually be smaller than some ofthe stars visible in the night sky.

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From a Distance

Directions:Directions:Directions:Directions:Directions: Follow each step and answer the questions as you explore the Mystery Box Lightsource.

1. Look into the box and draw a diagram of what you observe. Label parts of your diagram.Underneath your drawing make 3 observations that are not found in your diagram.

2. What do you think is the energy source of this light? Based only upon your observation, ex-plain why you think that is.

3. Share your diagrams and observations within your group.

4. Individually, record 3 questions you have about this mystery light source that cannot be an-swered by your recent observations.

5. Share these questions in your group and record the questions on a large sheet of paper. Postthe paper and with the class discuss which questions will be investigated.

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From a Distance (continued)

6. After your teacher assigns your group your question(s), brainstorm within your group thedesign of a special instrument that would help your group gather data that will answer thequestion(s).

7. In the space below, diagram and label the new instrument design. Give a brief explanation ofhow it works and what kind of data it will give. Include a list of the materials needed to makethis special instrument.

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Student Guidesheet

Make Your Own Spectroscope

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Spectroscopic Observation #1: Observing Spectra

DirectionsDirectionsDirectionsDirectionsDirections: Use your spectroscope to observe and record the spectrum for 3 light sources givenbelow. Then choose 2 light sources of your own (for example: streetlight, neon signlight, Television light, computer monitor screen light) and record your spectroscopicobservations. Do NOT choose the sun for this activity. When you’re finished com-pare your results with your classroom scientists.

1.1.1.1.1. Light Source: fluorescent lights in the classroomLight Source: fluorescent lights in the classroomLight Source: fluorescent lights in the classroomLight Source: fluorescent lights in the classroomLight Source: fluorescent lights in the classroom

2.2.2.2.2. Light Source: soft-white lightbulbLight Source: soft-white lightbulbLight Source: soft-white lightbulbLight Source: soft-white lightbulbLight Source: soft-white lightbulb

3.3.3.3.3. Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________

44444..... Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________Light Source: ____________________________

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Spectroscopic Observation #2: Mystery Gas Tubes

DirectionsDirectionsDirectionsDirectionsDirections: Observe and record using your spectroscope the spectrum for each mystery gastube. Then use the Spectra Reference Chart to identify what element is in each tube.

1.1.1.1.1. Mystery Gas Tube #1: ____________________________Mystery Gas Tube #1: ____________________________Mystery Gas Tube #1: ____________________________Mystery Gas Tube #1: ____________________________Mystery Gas Tube #1: ____________________________





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Spectra Reference Chart

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Spectroscopic Observation #3: Solar Spectrum

To figure out what elements a star is burning for fuel, scientists compare a star’s absorptionspectrum to the emission spectrum of an element found on earth. Let’s look at the Sun’s Spectrum.

Notice where the dark lines occur. Note the number and color where the dark lines are located.

Next, look at the emission spectrum for hydrogen. Look closely at the red and blue lines.

Is the red line located in the same place on the hydrogen spectrum as a dark line in the red areaof the solar spectrum?

Is the thick, blue line in the same place on the hydrogen spectrum as a thick, dark line in the bluearea of the solar spectrum?

Is the thin, blue line in the same place on the hydrogen spectrum as a thin, dark line in the bluearea of the solar spectrum?

You should have answered “yes” to all three questions.

So, if the colored lines from the helium spectrum match exactly to the location of the black lines inthe same colored areas on the solar spectrum, then that means that the sun is burning hydrogen.

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Spectroscopic Observation #3: Solar Spectrum (continued)

Follow this same procedure to compare the other elements found on the Spectra Reference Chartto the Solar Spectrum and list below the elements that the sun is burning. Then, draw the emissionspectrum for each element given.

1.1.1.1.1. hydrogenhydrogenhydrogenhydrogenhydrogen

2.2.2.2.2. ___________________ ___________________ ___________________ ___________________ ___________________

3.3.3.3.3. ___________________ ___________________ ___________________ ___________________ ___________________

4.4.4.4.4. ___________________ ___________________ ___________________ ___________________ ___________________

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Career Exploration Guidesheet

Career Comparison

DirectionsDirectionsDirectionsDirectionsDirections: Choose 2 of the careers covered on the Web site http://solar-center.stanford.eduor during the Webcast, and list 3 ways in which the two careers are similar and 3ways in which the two careers are different.

careercareercareercareercareer careercareercareercareercareer

How Are They Alike?How Are They Alike?How Are They Alike?How Are They Alike?How Are They Alike?

In What Ways Are They Different?In What Ways Are They Different?In What Ways Are They Different?In What Ways Are They Different?In What Ways Are They Different?

• Solar Glossary

• Web Work

48

Appendix

Solar Glossary

DirectionsDirectionsDirectionsDirectionsDirections: An interactive vocabulary crossword puzzle and word search can be found on theWeb site: http://solar-center.stanford.edu using the following words and theirdefinitions.

AngstromAngstromAngstromAngstromAngstrom an unit of measure equal to 10 meters

electromagnetic radiationelectromagnetic radiationelectromagnetic radiationelectromagnetic radiationelectromagnetic radiationthe transfer of energy by the swinging back and forth ofelectromagnetic fields

electromagnetic spectrumelectromagnetic spectrumelectromagnetic spectrumelectromagnetic spectrumelectromagnetic spectrumThe wide band of energy from the sun which consists ofinvisible rays and visible light. See diagram below.

elementelementelementelementelement a substance that cannot by chemical means be decomposedinto simpler substances

heliumheliumheliumheliumhelium a lighter-than-air gas that is a chemical element

hydrogenhydrogenhydrogenhydrogenhydrogen a lighter-than-air gas that is highly flammable; it is a chemi-cal element that is the lightest of all substances

infrared radiationinfrared radiationinfrared radiationinfrared radiationinfrared radiation invisible electromagnetic rays that have a longer wavelengththan visible light and is detected because of its heating effect

49

Appendix

Solar Glossary (continued)

light spectrumlight spectrumlight spectrumlight spectrumlight spectrum The array of colors (or wavelengths) obtained when whitelight is refracted.

refractrefractrefractrefractrefract to bend light rays by having them pass from one transparentmedium to another. For example, passing sunlight through aprism will cause the rays to bend as the speed at which thelight is moving is slowed. Each color ray moves at a differentspeed or frequency. The highest frequency is refracted themost with the lowest frequency being refracted the least. Thiscauses the white light to be split into bands of color.

ROY G BIVROY G BIVROY G BIVROY G BIVROY G BIV An acronym that helps us remember the order of the colors inthe light spectrum.

spectral analysisspectral analysisspectral analysisspectral analysisspectral analysis The study and analysis of the white light from celestial ob-jects; each spectrum identifies the type of elements containedinside the object.

SpectrographSpectrographSpectrographSpectrographSpectrograph an instrument used for dispersing and recording specificwavelengths of the electromagnetic spectrum

SpectroscopeSpectroscopeSpectroscopeSpectroscopeSpectroscope an instrument used to form and examine spectra

starstarstarstarstar a large sphere of hot, glowing gases that appears as adistant pinpoint of light in the night sky

sunsunsunsunsun the star closest to the Earth that is a large sphere of hot,glowing gases and gives off electromagnetic energy to theEarth

visible lightvisible lightvisible lightvisible lightvisible light the part of the electromagnetic spectrum that can be seen bythe human eye

wave frequencywave frequencywave frequencywave frequencywave frequency the number of times a wave crest passes a point in a second

wavelengthwavelengthwavelengthwavelengthwavelength the distance between 2 successive wave crests

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Appendix

Web Work

http://solar-center.stanford.edu/http://solar-center.stanford.edu/http://solar-center.stanford.edu/http://solar-center.stanford.edu/http://solar-center.stanford.edu/

This site contains an interactive vocabulary crossword puzzle and word search using the solarglossary words. It also has an interactive explanation of the electromagnetic spectrum. Celestialspectra are also available to be viewed and analyzed in conjunction with the Science Explora-tions: Spectroscopic Observations and Reading a Spectrum.

http://image.gsfc.nasa.gov/poetryhttp://image.gsfc.nasa.gov/poetryhttp://image.gsfc.nasa.gov/poetryhttp://image.gsfc.nasa.gov/poetryhttp://image.gsfc.nasa.gov/poetry

Both teachers and students can use this site for lots of easy-to-understand information about thesun and various research missions that have collected much data about the sun. Teachers will findadditional classroom activities and resources useful for their students. The “Multimedia” buttonoffers informative animations and video footage that illustrates concepts about the sun.

http://helios.gsfc.nasa.gov/http://helios.gsfc.nasa.gov/http://helios.gsfc.nasa.gov/http://helios.gsfc.nasa.gov/http://helios.gsfc.nasa.gov/

An upper middle school to high school level Web site that offers grade-level appropriate text withinformative diagrams. This is a good resource for both teachers and students.

http://www.passporttoknowledge.com/sun/earth/sun_earth.htmlhttp://www.passporttoknowledge.com/sun/earth/sun_earth.htmlhttp://www.passporttoknowledge.com/sun/earth/sun_earth.htmlhttp://www.passporttoknowledge.com/sun/earth/sun_earth.htmlhttp://www.passporttoknowledge.com/sun/earth/sun_earth.html

This site offers even more helpful solar resources.

http://www.websites.noaa.gov/index/htmlhttp://www.websites.noaa.gov/index/htmlhttp://www.websites.noaa.gov/index/htmlhttp://www.websites.noaa.gov/index/htmlhttp://www.websites.noaa.gov/index/html

The weather service also provides information on the latest solar image and gives “space weatherreports” in the form of a solar-geophysical forecast. It offers excellent data that is graphed andarchived.

sun and stars - stanford solar centersolar-center.stanford.edu/activities/sunandstars5-8.pdf · 5....

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